Anybody who tries to approach Eric Rohmer's new feature, An Autumn's Tale, expecting mist, gloom and mellow fruitfulness is likely to be disappointed. The two main characters may be women in their forties rather than the chic twentysomethings who have appeared in most of Rohmer's recent movies. They may be melancholic about the state of their love lives. (As one sighs wistfully to the other, "all the best men are taken".) The comedy may be tinged with sadness. But the truth is, the late-summer sun blazes down throughout. Regardless of the romantic complications, the tone of the film (the last of Rohmer's "Tales of the Four Seasons") remains remarkably cheerful. But for once, Rohmer was thwarted by the weather. "He wanted more autumnal colours" reveals the actress Alexia Portal, " but the colours stayed green and the light was very, very soft."

Rohmer, now well into his seventies, is the most elusive of directors. It used to be claimed that not even his wife knew he was a film-maker. "Rohmer" itself is an alias. (His real name is Jean-Marie Maurice Scherer.) When An Autumn's Tale was unveiled in Venice last September, the director wasn't there to accompany the screening. Instead, he sent his three leading ladies as emissaries.

Interviewed one balmy autumn afternoon on the terrace of the Excelsior (the most luxurious hotel on the Venice Lido), they talked about him with reverence and affectionate curiosity, as if they were describing a distinguished but eccentric elderly relative.

One of them, Beatrice Romand, first met Rohmer 30 years ago, when she auditioned as a 17-year-old for Claire's Knee (1970). She recalls being shown into a dark room with opium pipes hanging on dark red walls. "I saw this man, very thin, very beautiful, with his blue eyes piercing me." She was deeply suspicious. "I was thinking maybe he was a director of porno films. All I wanted was to get out of that room."

On the face of it, Rohmer and Romand had nothing in common. Whereas the film-maker was a professor, a reserved, academic figure already in his forties, Romand was young, knew nothing of movies ("I didn't have money to go to the cinema") and hadn't even been to university.

"He was an intellectual and I was somebody from the heart," is how she characterises the difference between them. Nevertheless, she won the part in Claire's Knee and has worked with Rohmer many times since. Over the years, she believes, he has become less academic, "less like a professor from the university ...he's now more involved in life than the abstraction of literature". He clearly regards her as a muse. "Maybe it's simple flattery," she says, "but each time I'm shooting a film for him I feel him looking at me with jubilation, and it gives me incredible pleasure."

Everything about Magali, Romand's character in An Autumn's Tale, suggests ripeness. She's a wine-grower whose vineyard (in stark contrast to those of her neighbours) is messy, luxuriant and full of weeds. She won't use herbicides in case they ruin the taste of her vintages. Nor are her relationships with her children and would-be lovers any tidier than her vineyard.

Rohmer tracked down a real wine-grower in the South of France as a model for Magali. Says Romand: "He presented me with this woman, saying `Beatrice, she's not a sexy woman'. She's a little bit fat, a little bit clumsy. She doesn't wear make-up. She's spontaneous and she has large gestures. I copied them exactly as he wanted." Most important of all, says Romand with a smile, Rohmer didn't want Magali to be "refined".

Like her character in the movie, Romand in person is imperious, scatty and very funny. She flits between English and French, and clucks and scolds whenever she is asked what she believes to be a stupid question. She trails a kind of benevolent chaos in her wake. "Comprenez!" she fires out when her interviewer scratches his head after a long, rambling answer about the difference between written French and spoken French. She also disapproves, she confides, of how the once-meticulous Rohmer now sometimes lapses into slang. There were occasions when she had to set him straight about his use of grammar. "He told me, `Beatrice, say it like that.' I said no! Now, I am very proud that I know 'ow to talk literature. I want to say it correct!"

Not that she has anything but respect for the gentle way in which Rohmer habitually treats his cast. "He is cool, as young people say."

Marie Riviere, who plays Magali's best friend, has also worked with Rohmer before, starring in The Aviator's Wife (1980) and The Green Ray (1985). "I have the impression he hasn't changed ...he's even more quiet today ...a quiet man, a very, very wise man," she ruminates.

An Autumn's Tale is full of private moments between Magali and Isabelle, and between Magali and her son's beautiful young girlfriend, Rosine (Alexia Portal). The main topic up for discussion is men: their shortcomings ("they're all idiots or perverts"), what they are good for, and how they should best be snared.

What does a septuagenarian such as Rohmer know about the innermost yearnings of young and middle-aged women?

"He is accurate, but I don't know why. He finds something poetical in what women say or do. He understands," confides Riviere. "He talks about universal things. That's why the films don't get old with time," suggests Alexia Portal. "His vision of the Nineties generation is very accurate, especially in A Summer's Tale and An Autumn's Tale."

Portal scoffs at the idea that Rohmer is out of touch by comparison with the young mavericks of French cinema, figures such as Mathieu Kassovitz (La Haine), Francois Ozon (Sitcom) and Gaspar Noe (Seul Contre Tous). "He doesn't wear fashionable clothing, but that's why many young people can recognise themselves through these characters."

As for his directing style, all three women describe him as the most unobtrusive of film-makers. "He doesn't give direction at all," says Portal. "He doesn't like to talk about the psychology of the characters ... he doesn't want the actors to think too much about what they're going to do and say. He has a small crew which always works quickly.

"It's very pleasant shooting; it's not heavy and technical," adds Riviere. "We're not kept waiting for a long time, he never does more than one or two takes, so we're not tense ...it's like in life."

He tends to shoot in three-minute takes and there are no restrictions in terms of movement - the camera will follow the actors. "But every comma, every word is important. There is no improvisation," says Portal. "And if he gets bored or doesn't like the light, he'll just pack up for the day."

These three actors are trying to be helpful. They answer every question thoughtfully and politely, but somehow they just can't bring Rohmer into focus. At the end of an hour's conversation, he remains as mysterious as ever. Beatrice Romand makes him sound a little bit like the Scarlet Pimpernel. "He is always surprising ... you wait for him here and you find him there."

Portal agrees. "He cultivates an air of mystery about himself."

That doesn't mean that Rohmer is a misanthropic magus, pulling the strings behind the scenes. An Autumn's Tale is a gentle, warm-hearted comedy that will be accessible to all audiences. It is just that the man who made the film is hard to fathom. On one level, Rohmer's actors are perfect spokespersons for him. The more they try to reveal, the more inscrutable they make him seem.